Article comprising cord bonded to rubber by a vinylpyridine adhesive



Patented Oct. 2 8, 1952 UNITED STATES OFFICE,

Q 2,615,826 v AR'ITGLE COMPRISING co n v BONDED I o BY A VINYLPYRIDINEADHESIVE Gert midi) MalloryfAkrom and Theodore R; Ten Broeck, GuyahogQaFalls;- Ohio a Si'gnors to Wi'ngfoct Corporation, Akron, Ohio, acorporation of'DelaWare No Drawing; Application August 2, 1946 SerialNo. 6813940;

This: invention relates. to an improved adhesive for bondingreinforcingqoidsto ruhloer to a reinforcing cord treated. withtheadhesiveand to a. rubber article having a cord-bonded therein bymeans of the adhesive. p i

In themanufacture t rubber articles, includmg, pneumatic tires andmechanical ruljobe-r goods, the life of these articles depends to agreat extentuponthe reiniorcernent mployed and the ability to properlyjoin the reinforcing material tothe: rubber. Reiniorcing; materialincludes cord and, fabric made therefrom and may he a.- riatural textilematerial as, for examplecotton, or a cellulosicmaterialas, for examplerayon, I

oran polyamide reaction product as,v for example ny1on-, or cablemadeout'offine steel wire. Each material presents. a. di'fierentadhesive problem. '(fonsiderable exl'aer'ie'ncev has. been gained inbonding cotton cord to natural riibjo'er. Lessi s known about the properbonding orrayon and h mn to bothiiaturaland synthetic rubber; Natuifalrubber. latex. rias. ion l teen. use in solvin this, problem. ofCoretta-runner adhesion with higher, speeds required for the; aminedemand for longer 'lifahimproveihents had to be made. and various compouding, iri fidicnts were added to. the fiaturai'ruh er latex; incliidiingsuch proteir'ifaceous mater a is as casein and such ream asphenol-formal ehyde arid re undermined by Water aiid soiiie "sol and"dh'i'fiot' havefthe ties at adh sicn at h h temperatures... AlS, thesetdl'ie a terial, but. even here aahesive cf this typetendency tocoaguiate While bifig lisd iii production and to-- set up aftertheyhave, been applied to. the reinforcing material and before the;reinforcing; materialhas been calendered onto: the rubber which is tobe. reinforced.

It has now been discovered that. theseproblems may be solved by using:an: adhesive contai'ning, the; copolymer of a vinylpyr'id-ine mono= merand a 1,3-diene monomer. It has also been discovered that anexceptionally successful. ad-

hesive may be prepared by mixinglthe-vinylpyridine-diene copolymer witha'butalastic as, for; example a'butadi'ene'rubber, which adhesiveshows'gexceptional bonding power whenjnsed in the manufacture ofsynthetic. rubber articles;

A further improved adhesive is produced when a resin or aproteinaceousmaterial such as casein is added to; the vinylpyridine-diene copoly'merand hutalastiolj t v The vinylpyridine-diene copolymercomponent of!thisadhesive is theproduct resulting from the copolyrneriied'hy any ofthe-conventional meth= ods WGiI kIflOW-Il in the art; such as bulkwith;- out. solvents;- or d-i-luents; in the presence ofi an inert.solvent, or inemulsion. "The proportions of the monomers initiallypresent inthe.emu l+ 9* 9l ize ma r d: ver a wide range The ratio of;dien'e toivinylpyridine may range: iror'n about .95/5 to about 20180 ,1.and it. is desired to user a. ratioin which the; diene' is present in apredominant amount; A prre fer-red ratio range ot diene. tovinylpyridineis between ab i tBO/ O and about.to/{30 A standard formulation for thepreparation of a? copoiymer. of 1,3-hutadiene and-4 2-vinylpyridine'comprisesthe use of 180 parts of water penparts of monomer; 5% of. anemulsifier: as; for example. sodium stearate and: 0.3%; of a.- cat;alyst as; for example potassium" persulfatez additiontoqthis standard.for:'milatiom antioxig dants and;modifierss-may be-addede a In order toemphasize the advance made over known adhesives, comparative data aredisclosed below and these data are based upon identical test conditions.All test specimens were prepared in the same way. For example, naturalrubber test specimens were cured at 200 pounds per sq. in. pressure forminutes at 300 F., and the synthetic rubber test specimens weresimilarly cured but for minutes. All adhesion values are given in poundstensile, as developed in pulling a cord out of a block of rubber wide,.1" thick and about 1" long. Further description of this test may befound in Bulletin AIC-99 issued October 1945 by the Southern RegionalResearch Laboratory of the U. S. Department of Agriculture. I

In order to further emphasize the exceptiona results obtained with theadhesive of this invention, test data is given with respect to bothnatural rubber and synthetic rubber reinforce'd with cotton cord, rayoncord and nylon cord. In

the case of cotton cord, the specifications call for about a 11 inchstaple cotton spun as a 16syarn and twisted 4/3 construction with atwist of 14 Z per inch in the single, 16.5 2 per inch in the ply and10.6 8 per inch in the cable. The rayon cord used in the examples isknown as 1100 M denier twisted 2 ply with a single twist 'of 13 Z perinch and'a ply twist of 1328 per inch. The

nylon cord used in the example is known as 210 denier 4/2 constructionwith a single twist of 1 turn either 2 or S, a ply twist of 12 2 turnsper inch and a" cable twist of 10.5 8 per inch.

Very. .poor adhesion is obtainedbetwe'en the -nylon and rayon type ofreinforcing cord and natural and synthetic rubber without treatment. Bynatural rubber is meant any rubber of a botanical' source, includingHevea. brasilz'ensis, etc. By synthetic rubber is meant any polymer of a-1,3-diene or copolymer with other polymerizable compounds, includingthe copolymers of 1,3- butadiene' and styrene, acrylonitrile, etc. All

data is' given in terms of the results obtained in the production ofbonds with the Hevea brasiliensis. natural rubber and with the1,3-butadienestyrene rubber commercially known as GR-S, and in which-75%' of 1,3-butadiene is copolymerized with of styrene in emulsion."

Under ideal conditions, untreated rayon and nylon cord may be bonded toboth natural and synthetic rubber by an adhesive force of not 'more than7 to 9 pounds tensile. Cotton cord "develops a value of between '12 andabout 17.

When nylon-is treated with a rubber latex, some improvement is noted.For example, treatment with an artificial dispersion of rubber, whichmay be, for example, a whole tire reclaim dispersed in water, increasesthe value to 12 for both natural and synthetic rubber, and increases thevalue for rayon'to about 15 for natural rubber and 17 for syntheticrubber. r

Treatment of nylon, rayon and cotton with uncompounded'GR-Sla'tex has nobeneficial effect with either natural or synthetic rubber. However,treatment of nylon with the 1,3-butadienez-vinyl-pyridine copolymer,hereinafter referred 'toas' B/VP, increases the bond by 37 on naturalrubber and on synthetic rubber, hereinafter referred to as GR-S,increases the bond 100%. For'rayonon natural rubber, an increase of 79%is observed, and an increase of 175% is obtained on GR-S. A substantialincrease is obtained for cotton on GR-S. In order to improve the bondingof each reinforcing material to natural rubber, it has been found thatresults comparable to those obtained on synthetic rubber may be producedwhen the 3/ VP latex is blended or mixed in equal proportions with GR-Slatex. A preferred adhesive has a solids latex content ranging from 10%to 26% and may be produced by using a, 1:1 ratio of GR-S latex to B/VPlatex, depending on the mechanical treatment of the cord used. A mixtureof 8% GRr-S latex and 8% B/VP latex produced bonds on natural rubberwith nylon, rayon and cotton ranging from about 55% for nylon to about33% for rayon to about 18% for cotton, better than the' bondsproducedusing the B/VP latex alone. Similar results were obtained on syntheticrubber using the same adhesive.

The ratio percent of B/VP latex to GR-S latex m the adhesive may rangefrom about 14/2 to about 2/14, to produce an adhesive having a totalsolids content for the latices of 16%. However,

it is 'preferred to use a ratio of 9/7, since this ratio gives anaverage bond for nylon, rayon and cotton on both natural and syntheticrubber, which is slightly better than the other ratios.

stage A phenolformaldehyde resin or a resortcinol-formaldehyde resin. Vr A sodium phenylate caseinate solution was made up containing caustic(sodium hydroxide), 1% phenol and 12% casein. The caseinate was added invarying amounts and the latex solids or rubber hydrocarbon solids weremaintained at 16%. The addition of 0.5% casein to the 9/7 B/VP GR-Sadhesive produced a bond for nylon on natural rubber ranging from 49 to86%, for rayon on natural rubber ranging from 11 to 18% and for cottonon natural rubber up'to about 7% higher in each case than the bondproduced using the same adhesive without the resin component. i

Comparable improvement is observed when using additional 0.5% incrementsof casein up to total of 3.0%. Similar results are also observed onsynthetic rubber. Although theaddition of casein to the latex blendformulation produces desirable increases in adhesion, the presence ofcasein does cause certain difficulties when used in production andtherefore it is desirable to re-.

place the casein component and at the same time retainthe desirable bondstrength.

Desirable results are produced when a stage A phenolformaldehyde resinis used. The resin is a water-soluble thermosetting phenol; formaldehydecondensation product which is prepared by reacting a phenol with amolecular excess of an aldehyde, for example forma'lde hyde, in thepresence of an alkaline catalyst until a water-soluble product isproduced. More par ticularly, the resin may be prepared by reacting 50parts of phenol with 90 parts of 37% formalg dehyde in the presence of.1.5 parts obsodigim hydroxide at 90 C. for 50 minutesin a water bath.The stage A phenolformaldehyde' resin may be added in 0.5% incrementsbetween "about 0.5% and about 3%. Adhesion values compara''-' ble tothose obtained when using casein were ob tained when using the stage Aphenolformal= dehyde resin in place of the casein in the above notedformulation. It was observed, however, that consistently betterresultswere obtained with the stage "A phenol-formaldehyde resin formulationthan in the casein formulation? :Thusgthe' use. of the stage"A phenolformaldehyde resin has a stabilizing influence on the adhesive producedand insures reproduct n of results.

Another formaldehyde resin that may be used to great advantage in theadhesive formulation is the resin produced by reacting resorcinol withformaldehyde. One half to 3 mols of CHzO may be'used per mol ofresorcinol and the reaction maybe conducted in water at roomtemperature. A similar series of tests involving rayon, nylon and cottonon both natural and synthetic rubber indicates that this formulationproduces exceptionally desirable adhesions regardless of the type ofcord and rubber being bonded together. 1 Values as high as, 25.2 poundswere obtained or cotton on natural rubber, 25.6 pounds were ob tainedfor nylon on natural rubber, at which point the cord broke, and valuesas high as 20.6 pounds were obtained for .rayono-n natural rubber.Similar values were also obtained for these difierent cords on syntheticrubber. The same desirable results were noticed when employing theresorcinol-formaldehyde resin in amounts between about 0.5% to about 4%.

v It m preferi'ed to use about 2.0%, based upon the total ad sive.

In addition to'the remarkable adhesion produced between nylon cord andrubber, it has also been was performed by-hand dipping the cord in thelatex, followed by- 7- /2 minutes of drying at 250- F. and thenembedding the treated cord in the standard rubber block and vulcanizingas described above to produce the test specimen.

The commercial application of the adhesion comprises running thecordthrough a. machine in which the cord is dipped in the adhesive containedin a dip tanlr and strippingoff the excess adhesive by means of gravityflow, squeeze rolls 91? air liets, drying in; an oven or in a chamber offast moving air at, a rate to prevent. blistering; or the. adhesive awayfrom the fibers, followed by a. hi h r a e; ying d; in process.

Each of the ioregoing; tests involving the use oiia. formaldehyde resinwas. based upon a formu- .6 B/VP component together. with the GRr-Slatex and a resin, has good heat-ageing characteristics. However. thesecharacteristics are improved when theresin component is made; withoutthe use of an alkaline. substance or when only. using a minimum amount.

Maximum results, using the adhesive 01!:- this invention. are obtained:when the B/VP latex is. used in an. amount of about. 13%. the GR-Slate): in an amount of about 1.0% and the resin in amount."- of about3%, the resin being prepared using 25% excess formaldehyde and passingthe cord through the. adhesive. at. a. rate. to permit a. solidspickmpofabout '10, to. 2L.%.- However. in view of the exceptional resultsobtained. when using the B/VP component, either alone or with otherlatices and resins, these conditions are not critical but;ar'emerelythose referred. The B/VP component may be present ima-namount: between 'aboutfi to about 15%; the GR-S componentmay be presentin amount between about 5 to about 10%; and" the, resin componentmay bepresent in an amount between about 1% and about 5%. each based upon thetotal components present.

The preparation. of the adhesive'is". carried out by mixing, thecomponents together and, com.- pleting the reaction between.thevariousreactable eomponents,.. Such a mixture comprises theformaldehyde component. of; the. 'resirr, .the phenol or resorcinolcomponent of. the resin. and the latices. It has: been observed',howeventhat. when using a phenol-formaldehyde type; resin; best resultsare obtained when the phenol'a'nd formaldehyde are reacted to stage "Abetore mixing with the latices. Good results are obtained, however, withthe resorcinol-formaldehyde resin using either method.

The; following tables emphasize the exceptional and unexpected resultsobtained using an ad- 1 hesive containing a B/VP component.

lation. containing 9%.B/V1? latex. and, 1%. GR-S.

latex plus 2% of a resin prepared by reacting over twice the theoreticalrequirement of formaldehyde or by reacting 2 mols of formaldehyde with 1mol of phenol or resorcinol. In view of the fact that excessformaldehyde is objectionable from the standpoint. of fumes. atthevdipmachine in produc io it. s. prefer ed to use the mi um. amount. offormaldehyde necessary to bring about: desirable results. Thus; equalmolecular amounts of formaldehyde to 25% excess formal dehyde may beused. However, where a plasticiz ing action is. desired as. is desirablewhere: the. treated. cord: is. to. be storedfoi: sometime. then.

xce s; of resorc nol. s. t be use 1 An important characteristi th t;aoord, adher sire; must. have, is an ability to. maintain its. ad-

and. tested; either. at. room, or. high. temperatmte Table I shows theadhesion developed between untreated cord and natural and syntheticrubber.

TABLE I Adhesion Rubber: I

Cotton Rayon Nylon Table II shows results obtained when treating thecord with synthetic rubber latices and reclaim natural rubber latex.

TABLE II Adhesion;

Latex Rubber-- t Cotton Rsyon- Nylon Reclaimedrubber Natural..- ,ltfio15.2 l2..0 Do: GIL-S..." 17.8 17.4 1250 GE's; NaturaL. 17.4 8.6 8.0

0 G-R S 13:8 6:2 5L8. B/VI Natural 17.0 15.0' 11.111 0 G'R-S 21.6 19.2"1 x03 Table: III. shows: results: produced using. blends The present.adhesiv involving. the use of the ct latices.

8 Table VI shows the efiectof. adhesive. dilution These a1de-.

TABLE n A A mfim I... ..r.. e d n m afi u m k nmmw mm m W m m m m.wmnnnnnmm .SV, m n m B n m t N .0 e sa o i .m m seaweeds m seas .i a 7d t v hssaiese e R 1111 o t 9 y R 3 11111111 n e mm seen 2 GR .a 3 mw tn c m 1 m% m s ss m xs n m 0 Mann MN m m a m m m mmnmumnnn W W M 6 086Ma e m 2 .m 7- M m 84410138 m A r N nnwn mm m c s 1 m m A r n nnnwmmnwme B w. %m nw mo m M d H 0082 25. W .1 p q M u n 00262 6888 e R 0 902s eO S X D 2 M R. o. 9 9 9 &&9 7 U .1 R 2111 S2 6 E I W mlllllll T .Z In ht o c. h. a a m Rm 5 a 7 m U m m R .t h m s bs m .m a 1 2 n m w m wsesses m a sun at n m d x a m wnnnmnnwm 7 3 1 n e T C m W K r G D. a m t9 l n m i m m. m 5 V@ m .m o m a m d r 5240243; S .0 MN. 1194 /H b w/ SS T 7n S 8 6 R Be a 7 m I a T F d 9 2 e X..0 n... .n a e o v O h 2 .1 0e c {R D n .110! 5 M .e B e n y u. 0 A W b 2 1. S S S .m n 6 .n 5 5 m ws 2 a n ai u .1 AJ .1 s. l .n u m 62204682 ...O I m m .m w. s z mi. n syun. oe s 1 N 11.11111 Lb a I m N NEH tsm D 9 2 a i H e a n R H n m m 242 n.m. n i m CH .1 .6 0. 008 30 S L. n w Y immense? mew. bh m m fi w e oh 1 .1 l .d S D. r 4 d m 1 21 1 u 8 V. 12 hEO A T. w m 11 nc m m: w26284880 0 A HEW. 0% $0.0. n 87.? 096 h 0...... nm c2 RDD M M E112m2l1 mhm w mph 0 a. at a 2 in g 2 i M? v z n 1 w m n n r u n .1 W 0 mm m 6 u gl. e S b 1 o r e m m a m fa muse r a E I 5mm .a e N 8 r O wee b w T mm.s I cmmm mm P 00888888 5% h H m farm. V u u. I R n 8 e. x mm 44 WI 0. MB n W m W 0 r f 0 m m m es%l hfi e S 2 O 0 d L S 88008888 to t t z n hV. t N e n w an mn t m G 44. m d NG bomb v w m W6 6W m w d m r w s 5:w5. P 0. 88880088 4 1 C8 OSm a .4; T .1 .7 I 1 7.W t mm. .9 .P on 9 amFrom the above table it. may be observed that; the casein resins take a.relatively long baking; 85 time to develop best adhesion and that thealde-i hyde resins produce good adhesions in thebegim. ning and tend tofall off with time. hyde resin type adhesives are ideal for train: Nylondip and calender operations or pickless calender- 70 ing in view of thetime interval between the dip and the calendering. e

' Table VIII shows the results obtained when reacting the formaldehydeand phenol before addition to the latices and when adding the 11101105":mers in the unreacted state to the latices.

Cotton yrene rubbery '-v'iny1 pyridine rubbery co- TABLE V 9/? latexwith resorcinol-formaldehyde adhesion Rubber Naturai.. GRS

RHC' symbolizes rubber h of cord to natural and synthetic rubber RHC,Percent Cord broke. I77 symbolizes 9% butad1ene plus 2% of aresorcinoI-formaldehyde resin.

polymer and 7% butadiene- TABLE VIII Adhesion Formula, percent ConditionPercent resin pick up GR-S Natural gf fl j 1 monomers 17.4 14.4 17.617.4 18.2 17.1 12. 4 15. 8 17. 2 20.0 18. 7 10. 6 12. 2 13. 4 15.0 15.522. 4 23.6 23. 6 27.0 17.6 23.6 27. 4 22. 2 21. 4 19. 8 25.0 26. 8 28.024.8

1 13% B/VP10% GR-S plus resin as shown. Percent pick up means the amountof adhesive by weight picked up by the cord as it is run through the diptank containing the adhesive.

In view of these results it is preferred to react the formaldehyde withthe phenol before addition to the latices.

Table IX shows the effect of varying the amount ofresorcinol-iormaldehyde resin used with 13% B/VP latex and 10% GR-Slatex.

TABLE IX 1 3 B/ VP/ 1 0 GR-S with resorcinolformaldehyde resin Percentpick up means the amount of adhesive by weight picked up by the cord asit is run through the dip tank containing the adhesive.

Suitable changes may be made in the details of the process withoutdeparting from the spirit or scope of the present invention, the properlimits of which are defined in the appended claims.

We claim:

1. A bonded composite material comprising a cord embedded in avulcanized rubber, and a composition comprising a copolymer of a 1,3-diene monomer and a vinylpyridine monomer, a rubbery copolymer ofstyrene and 1,3-butadiene 4. A bonded composite material comprising acord embedded in a vulcanized rubber, and a composition comprising a,copolymer of a vinylpyridine and a 1,3-diene monomer, a rubberycopolymer of styrene and a 1,3-diene monomer and a stage Aphenol-formaldehyde resin, the composition forming a bond between thecord and rubber.

5. A bonded composite material comprising a cord embedded in avulcanized rubber, and a composition comprising a copolymer of avinylpyridine and a 1,3-diene monomer, a rubbery copolymer of styreneand a 1,3-diene monomer and a resorcinol-formaldehyde resin, thecomposition forming a bond between the cord and rubber.

6. A bonded composite material comprising a cord embedded in avulcanized rubber and a composition comprising 5 to 15% of a copolymerof 1,3-butadiene and a vinylpyridine, 5 to 10% of a rubbery copolymer ofstyrene and a 1,3-diene monomer, and. '1 to 5% of a resin selected fromthe group consisting of a stage A phenolformaldehyde resin and aresorcinol-formaldehyde resin, the composition forming a bond betweenthe cord and rubber.

GERALD D. MALLORY. THEODORE R. TEN BROECK.

REFERENCES CITED The following references are of record in the file ofthis patent:

and a phenol-formaldehyde resin forming a bond between the cord andrubber. UNITED STATES PATENTS 2. A bonded composite material comprisinga Number Name Dat cord embedded in a vulcanized rubber. and 2 2,256,153Riehl Sept. 16, 1941 composition comprising a copolymer of isoprene2,291,208 Brown et a1 July 28, 1942 and a vinylpyridine monomer, arubbery co- 2,294,826 Pieper et a1 Sept. 1, 1942 polymer of styrene and1,3-butadiene and a 2,314,976 Gazdik et a1. Mar. 30, 1943phenol-formaldehyde resin forming a bond be- 2,314,997 Lessig et a1 Mar.30, 1943 tween the cord and rubber. 2,314,998 Lessig et a1 Mar. 30, 19433. A bonded composite material comprising 9. 2,354,426 Briant July 25,1944 cord embedded in a vulcanized rubber, and a 2,360,946 HershbergerOct. 24, 1944 composition containing 10-26% solids of a 00- 2,397,050Sarbach Mar. 19, 1946 polymer resulting from the polymerization of 9.2,402,020 Cislak et a1 June 11, 1946 mixture containing 1,3-butadieneand 2-vinyl- 2,561,215 Mighton July 17, 1951 pyridine present in abutadiene-vinylpyridine ratio of 95/5 to 20/80, a rubbery copolymer ofFOREIGN PATENTS s yrene and 1,3-butadiene and a phenol-formaldehyderesin the composition forming a bond fig f gg i between the cord andrubber.

1. A BONDED COMPOSITE MATERIAL COMPRISING A CORD EMBEDDED IN AVULCANIZED RUBBER, AND A COMPOSITION COMPRISING A COPOLYMER OF A1,3DIENE MONOMER AND VINYLPYRIDINE MONOMER, A RUBBERY COPOLYMER OFSTYRENE AND 1,3-BUTADIENE AND A PHENOL-FORMALDEHYDE RESIN FORMING A BONDBETWEEN THE CORD AND RUBBER.